Effect of bisphenol A on murine immune function: modulation of interferon-gamma, IgG2a, and disease symptoms in NZB X NZW F1 mice.

To investigate the effects of the estrogen receptor-binding molecule bisphenol A (BPA) on murine immune function in vivo, we fed a low dose of 2.5 micro g BPA/kg body weight/day to both normal C57BL/6 and lupus-prone NZB X NZW F(1) (NZB/NZW) 5-week-old mice for 1 week. Analysis of concanavalin A (ConA)-stimulated splenic mononuclear cells by ELISA demonstrated that BPA-fed C57BL/6 males produced, on average, 40% less interferon-gamma (IFN-gamma; p < 0.01) and C57BL/6 females 28% less IFN-gamma (p < 0.05) compared with controls. Treated female NZB/NZW mice were monitored for lupus disease symptoms, defined as proteinuria (> 100 mg/dL albumin in urine for 2 consecutive weeks). Before the development of proteinuria, BPA-fed NZB/NZW mice produced significantly less ConA-stimulated IFN-gamma than did controls and displayed an average reduction of 50% in immunoglobulin G2a (IgG2a) antibody production from lipopolysaccharide (LPS)-stimulated splenocytes (p < 0.05). It is striking that 5-week-old female NZB/NZW mice fed a 7-day low-dose course of BPA developed proteinuria an average of 7 weeks later than did controls. Once proteinuria developed, splenocytes were stimulated with ConA for cytokine analysis. The BPA-fed mice showed a dramatic reduction of 64% in IFN-gamma production and a 32% reduction in ConA-stimulated interleukin-10 (p < 0.05). The long-lasting effects of BPA on IFN-gamma and IgG2a production likely contributed to the increased symptom-free period of the NZB/NZW mice.